Abstract
Cold antibodies were separated from the sera of six patients suffering from the cold-haemagglutinin syndrome and from one patient with acquired haemolytic anaemia secondary to lymphosarcoma by dissociation of the specific antigen-antibody complexes. The eluted antibodies were studied (a) by immuno-electrophoresis along with the parent sera against horse anti-human serum and (b) by double diffusion in agar gel along with electrophoretically separated `γ(1) globulin'† against anti-19S `γ-globulin' rabbit sera. The protein forming the cold antibody was localized in the β(2)-M position on immuno-electrophoresis in each instance. It was found by double diffusion in agar gel to be immunologically identical with the protein forming the abnormal `γ(1)-globulin' electrophoretic peak in the parent serum. The results of these experiments indicate that the cold antibodies derived from patients with the cold-antibody type of acquired haemolytic anaemia are macro-molecular globulins.